115L AV15-X sub – One of a pair.


  • Member
    simon5 on #6100

    Thanks for this update. 3.2 ohms DC should give about 4++ ohms with music higher in frequency.

    6 hours, that’s a record, it takes much more time for me to do a box hehe ! Great work ! 😀

    Maybe you could compare your dual boxes to your THX Ultra2 subwoofer ? :mrgreen:


    Member
    russ.will on #6101

    I’ll have to wait until the review of the sub (and the speakers) is published, but suffice it to say I think you would be happy with the result.;)

    Russell


    Member
    simon5 on #6102

    I am happy for sure, but I hope you are also happy with the results, since it’s your subwoofers… :mrgreen:


    Member
    russ.will on #6103

    After all the help I received here, I thought it only fair to complete the build thread, so here’s the salient posts from the complete AV Forums build thread:

    Some glue detail. The idea is that the glue will fill the corner without squidging out onto the veneer:

    The clamps are only lightly tightened so as no to mark the legs and are only there to keep the legs true. Note the drivers doubling up as ballast to ensure they all glue level as well as square.

    Somebody earlier in the thread asked me to do a piccie with a CD in the frame for scale so I did it here:

    The eagle eyed will spot a finished grill in the background.

    I also bought some Sadolin Worktop Oil just to test on some offcuts of the solid oak and the veneer. I didn’t mind if it darkened a little, figuring that was unavoidable anyway, but I wanted to maintain the hue of the wood. I think the Sadolin oil does that reasonably well, plus it seems to equalize the slight colour difference between the two samples and brings the grain out really nicely, so I’m not going to mess any further and just use it:

    Once the tops go on tomorrow, I’ll just oil the damn lot. I can’t be arsed to try decoupling the top, as the subs weigh a tonne and don’t move anyway. After all, the top is a 58mm thick oak/MDF sandwich.

    Russell


    Member
    russ.will on #6104

    The end is nigh!:eek:

    In a good way though and what follows is the final steps toward that end.

    So, today’s progress was a grim determination to finish the build. After gluing the legs last night, the next step was to fix the tops, but as large lumps of wood sliding around on glue would introduce another delay (albeit, about an hour) I decided to glue ‘n’ screw again. Thus, I could work on the subs whilst the glue dried. Keeping the glue well inboard of the edges, I could slide the tops around on the glue until I was happy with the position and then drill four quick pilot holes for some 1 1/4″ No.8 screws. The really interesting glue:


    With the legs in place, I could finish the second grill which I forgot to photograph earlier. For anybody trying similar, I stretched the fabric to the midpoint of each side and stapled. I then stretched the cloth to the four corners and stapled. This simply left stapling the intermediate points in place and trimming the excess. On the first grill, I stapled a point and then worked my way round the frame. The end result was similar, but seemed to involve a lot more arsing about so I’d recommend the technique used for the second if asked. BTW, I was going to back the grill with felt as I was worried about staples scratching the veneer, but hammering the staples with a small hammer (every workshop needs several hammers) has submerged them into the MDF below the level of the cloth, so I shall probably leave it there:


    Next, onto the oiling. Nothing more complicated than pouring some oil onto an old cloth and rubbing it in. The butchers block tops seem to drink the stuff and in non too even a fashion, compared to the legs which took a once over and seemed happy. All oak is not the same. Here’s the halfway house. Note how the grain is brought out in all it’s glory:


    As that is the final stage, all that is left is some gratuitous subwoofer porn.

    A nice perspective shot:


    The backs, for people who worry about such things (I do – hence the veneer that no-one will ever see):


    Driver fit and finish:


    I nearly forgot! The grills which I’ve yet to show. I’m really pleased with these – Jam them under the table top, let go and plop! They’re in place. Nice:


    And finally an in-situ shot passed the right sub toward the left sub:


    I should at this point hand out some thanks to two co-conspirators. Even if they hadn’t jumped on-board once I’d chosen these drivers, they wouldn’t have rendered the project impossible, but it would certainly have been made it a lot more expensive by their absence. So thankyou for that leap of faith in trusting my judgment chaps – I could have been very wrong.

    Adam (AngleEyes), many thanks for you patience, support and ‘finding’ a well equipped workshop to get this underway. Dan (Moonfly), thanks for sending me free glue, magnets and gaskets – I salute you. Thanks chaps.:thumbsup:

    The End.

    Russell


    Member
    simon5 on #6105

    Very very nice work ! 8)

    Did the review of the speakers and subwoofers has been published, so you can publish your own subwoofers review ?


    Member
    russ.will on #6106

    I’m reviewing subs and speakers all the time – I’m an official reviewer for AVF, but that is limited to commercially available products. Still, I now have a very good benchmark to judge them by and it’s nice to have something to post about on forum as my ability to express my own personal views are now a bit more restricted than they used to be.

    Roll on the slot loaded bad boy we’re talking about elsewhere….

    Russell


    Member
    russ.will on #6107

    By way of an update, I’ve been running the twins for a while now and in that time, I’ve had a fair few commercial subs through these same portals. The twin AV-15Xs remain the benchmark, but they don’t have everything their own way.

    In terms of the plus points, for the money involved, I’ve yet to here anything that simultaneously offers the sheer kick in the chest coupled with room wobbling depth. For instance, I’m bending the room in much the same way that an SVS PB13U does and delivering the super clean upper bass and kick of a Paradigm Sub 1. It has to be said that as a predominant music listener, I’d take the latter over the former, even if we ignore the price difference and the awesome in-built EQ capabilities of the Paradigm which are worth a significant amount of cash in their own right. As commercial subs go, I’ve yet to sample anything that wibbles my frosset pouch in the same way at any price as the Sub 1 did.

    I also liked the way that the multiple drivers of the Sub 1 drives the room. Unlike anything else I’ve heard, it ‘feels’ much like the twin AV-15s do, even though they are far more widely spaced – As a single sub solution the Sub 1 is awesome. Even if we accept it’s limits sub 20Hz and frankly, if subs like the PB13 didn’t exist, you wouldn’t even raise this as an issue, in terms of commercially available subs at least.

    There is one area in which the Sub 1 revealed a weakness of the AE subs and it’s in the non-integrated nature of the poweramp in the DIY sub. Given the manufacturers specs and indeed an independent test on AVS, I have enough power to push the AV-15s up to just beneath their Xmech limits, according to WinISD and Unibox at least. I accept that the limits of such programs are not all encompassing, but as a DIYer, you don’t have much else to lean on. However, as a tester of commercial designs, I note that you can just turn the wick up and up and up and even if you know what you are listening for, the worst you can expect is a gradual reduction of the reproduction of the deepest frequencies. In other words, the top to bottom design integration of the best commercial subs results in a benign, graceful performance at the point of being over driven, such that you wouldn’t know it was really happening. It’s inaudible and it’s only the fact that you know certain frequencies are missing compared to previous experience that lets you know something is missing. It’s a sin of omission, but nothing worse.

    By comparison, the DIY subs match these limits and even exceed them, but over-step them far less gracefully. When the amp runs out of puff, you hear a hardening of the tone from the subs that lets you know the limit has been reached. This is NOT the fault of the drivers, nor the amp as both are delivering within expectations, but as neither knows what to expect from the other, the design as a whole cannot be designed to self limit in a soft way. The Sub 1 (as an example) given a certain piece of program material, at a given replay level, may hit it’s limits far more often, but you wouldn’t know it as it doesn’t ask itself to attempt feats it can’t match and in some ways, this results in a more satisfactory, or at least less worrying, reproduction.

    Now, it is worth mentioning that the Sub 1 costs double the total cost of my twins and indeed, nearer three times the cost of their basic construction minus the ‘prettification’ materials and as such, I really can’t complain about the performance/value ratio achieved – It’s absolutely awesome on that basis. But I just thought it worth mentioning as a factor nobody ever seems to mention when eulogizing about their DIY subs – You’re never quite sure where the limits are and if you’ll do damage when you reach them. With good commercial subs, this worry is much reduced. I’ll leave you to put a value on that quality.

    Russell


    Participant
    stryke on #6108

    Hi Russell,

    One of the things you can do is run the subwoofer channel through something like a DCX2496, Driverack 260, or even just a simple rack mount limiter. This will allow you to adjust the threshold and really soft limit the system. In most good amps with DSP you have this available, but in a straight power amp, you often need an outboard processor for this.

    John


    Member
    russ.will on #6109

    Now that’s double interesting as I have a DCX2496 that I picked up for a future DIY speaker project, but is otherwise laying around un-used.

    It looks like I shall be taking an interest in it sooner than I thought. 8)

    Russell


    Member
    simon5 on #6110

    Glad that you are happy with your subwoofers, it’s true that nothing is perfect, but at least John try to build superior stuff, and I think he’s got it ! 8)

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